With the continuous development of TFT LCD (Thin Film Transistor Liquid Crystal Display) technology, the TFT LCD has become an important display platform of modern IT and video products. The TFT-LCD controls the arrangement form of liquid crystal molecules through the electromagnetic field between an array glass substrate and a CF (Colour Film) glass substrate, so that the light through the liquid crystal deflects to form different penetration rates, thereby achieving the display principle. The certain time required for the liquid crystal molecules to turn from the deflection state to the normal state and then to the deflection state is called response time. The smear caused by the over-long response time of the crystal has become an important factor that affects quality of the TFT-LCD.
Smear refers to the phenomenon that the moving object leaves a residual image on the background or that the background leaves a residual image on the moving object, when the image of an object moving relative to a static background is displayed. The smear includes the bright smear and the black smear which include the point smear and the line smear. In addition, the smear includes the vertical smear and the horizontal smear from the point of direction. FIG. 1 and FIG. 2 respectively show display states of the bright smear and the black smear in the liquid crystal display. As shown in the figure, a black moving pattern 3 moves rapidly toward the left with a smear 4 behind. The smear 4 becomes the factor that affects the display quality, therefore how to accurately judge the smear extent has become an important basis for judging the quality of the display device.
The smear measurement at present mainly uses a simple flash to simulate forming of the smear and judges the smear severity through the comparison by visual observation. This method is unable to accurately and effectively judge the smear extent, therefore the display quality of the display device can not be accurately judged.